Amazon is cautiously venturing into on-premise private clouds by partnering with Eucalyptus Systems, a provider of commercial cloud infrastructure services based on open source APIs that are compatible with Amazon Web Services (AWS). However, that compatibility was never officially sanctioned by Amazon.

Until now.

CRN reports that the deal -- terms of which remain hazy -- will smooth the development of APIs that connect to Amazon Elastic Compute Cloud (EC2) and Amazon Simple Storage Service (S3). In a statement, Terry Wise, director of Amazon Web Services Partner Ecosystem, "Enterprises can now take advantage of a common set of APIs that work with both AWS and Eucalyptus, enabling the use of scripts and other management tools across both platforms without the need to rewrite or maintain environment-specific versions."

Since its inception, AWS has been the antithesis of the private cloud model. Available to practically any business of any size, its services have become popular with consumer-facing startups and Web 2.0 companies. Eucalyptus Systems, meanwhile, has been helping organizations build hybrid clouds that hook into Amazon's APIs.

Since Amazon never dropped the hammer on Eucalyptus, their relationship, however unofficial, was viewed by the industry as a sign of tacit approval. Nonetheless, many enterprises seeking hybrid cloud solutions have been hesitant to jump into the AWS-powered camp, given the apparent specter of legal and technical uncertainty hanging over their heads.

That changes this week, according to Eucalyptus CEO, Marten Mickos. "The ability to develop against a common set of market-leading APIs, for both on-premise and cloud deployments, is a big benefit for our customers and software partners," he said in a company statement.

Why now? OpenStack's meteoric rise may have some bearing.

OpenStack's Growing Influence

Within two short years, what started as a joint project between NASA and Rackspace has since ballooned into a partner ecosystem of over 150 organizations. These include industry heavyweights like Cisco, Dell, and Intel. Today, the race is on to build a market based on the open source cloud platform.

Public, private or hybrid, IP-wise there are no fundamental restrictions to deploying OpenStack clouds. This flexibility allows businesses to tailor their cloud strategy to their business needs, an attractive selling point for big businesses.

Now, by putting its weight behind Eucalyptus, Amazon is signaling that the company is willing to leverage its massive infrastructure and momentum in the cloud market to attract more enterprise customers.

Enterprise Applications: What Businesses Need to Know
An expert panel discusses current trends in enterprise applications, providing advice for businesses looking to refresh their portfolio of enterprise apps.WATCH NOW »